1. Field of the Invention
This invention relates generally to testing and improving signal lines, and, more particularly, to evaluating the quality of signal lines and standardizing the line connection.
2. Description of the Related Art
The testing and maintenance of signal lines, particularly transmission lines in telephone systems, is has become necessary and costly task. In telephony, it is common practice to transmit signals between a subscriber station and a central switching office via a two-wire bi-directional communication channel. The length of the transmission lines that carry telephone signals between the central switching office and the subscriber station can be quite large. As faster signals have been added to carry data over telephone lines, the quality of the transmission line has become critical, creating the need for periodic evaluation and adjustments.
Transmission lines generally have a natural characteristic impedance determined by cable construction and geometry. To drive a signal on a subscriber line while minimizing signal reflection from the far end of the subscriber line and maximizing the signal power entering the line, it is desirable to match the characteristic impedance of the transmission line with a termination at each end.
The Plain Old Telephone Service (POTS), which was designed primarily for voice communication, provides an inadequate data transmission rate for many modem applications. To meet the demand for high-speed communication, designers sought innovative and cost-effective solutions that took advantage of the existing network infrastructure. Several technological advancements were proposed in the telecommunications industry that made use of the existing network of telephone wires. The most promising of these technologies is the xDSL technology.
xDSL is making the existing network of telephone lines more robust and versatile. Once considered virtually unusable for broadband communications, an ordinary twisted pair equipped with DSL interfaces can transmit videos, television, and high-speed data. The fact that more than six hundred million telephone lines exist around the world is a compelling reason that these lines will serve as the primary transmission conduits for at least several more decades. Because DSL utilizes telephone wiring already installed in virtually every home and business in the world, it has been embraced by many as one of the more promising and viable options.
There are now at least four popular versions of DSL technology, namely Asymmetrical Digital Subscriber Line (ADSL), Integrated Services Digital Network Digital Subscriber Line (IDSL), Very High-Speed Digital Subscriber Line (VDSL), and Symmetric Digital Subscriber Line (SDSL). Although each technology is generally directed at different types of users, they all share certain characteristics. For example, all four DSL systems utilize the existing, ubiquitous telephone wiring infrastructure, deliver greater bandwidth, and operate by employing special digital signal processing. Because the aforementioned technologies are well known in the art, they will not be described in detail herein.
DSL technologies and Plain Old Telephone System can co-exist in one line (e.g., also referred to as xe2x80x9csubscriber linexe2x80x9d). Traditional analog voice band interfaces use the same frequency band, 0-4 Kilohertz (KHz), as telephone service, thereby preventing concurrent voice and data use. A DSL interface, on the other hand, operates at frequencies above the voice channels, from 100 KHz to 1.1 Megahertz (MHz). Thus, a single DSL line is capable of offering simultaneous channels for voice and data.
DSL systems use digital signal processing (DSP) to increase throughput and signal quality through common copper telephone wire. It provides a downstream data transfer rate from the DSL Point-of-Presence (POP) to the subscriber location at speeds of up to 1.5 Megabits per second (Mbps). The transfer rate of 1.5 Mbps, for instance, is fifty times faster than a conventional 28.8 kilobits per second (Kbps).
Telephone line characteristics can vary significantly when certain telecommunication equipment, such as telephones, facsimile machines, and xDSL transceivers, are connected to the line. It is desirable to perform many line tests on the telephone line for properly maintaining transmission lines. However, implementation of these tests can become manual-intensive and increase the costs of transmission line evaluation and maintenance. The industry lacks an efficient and automated method of performing line tests, particularly from a remote location. Furthermore, automated termination of nodes on telephone lines would dramatically improve the efficiency and quality of signal transmission.
Another use of the telephone system is the application of high frequency signals, approximately 7.5 MHz, being placed on the transmission lines to facilitate local network connectivity for multiple electronic products within a subscriber station. When employing high-frequency network applications on the transmission lines, an evaluation of the wiring within a subscriber line is desirable. Currently, the industry lacks an efficient method of checking the integrity of the transmission line and configuring the transmission line for the purpose of local networking.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
According to one aspect of the present invention, a method for testing, configuring, and evaluating a transmission line is presented. The method includes receiving a set of command and data signals through an input/output interface and processing the command and data signals from the input/output interface for controlling at least one relay. The method also includes activating at least one switch for testing and improving a transmission signal line using the relay and includes testing and emulating the transmission signal line based upon the activated switch. The method also includes configuring the transmission signal line based upon the testing and emulating.
According to another aspect of the present invention, an apparatus for testing, configuring, and evaluating a transmission line is provided. The apparatus includes means for receiving a set of command and data signals through an input/output interface and means for processing the command and data signals from the input/output interface for controlling a set of relays. The apparatus also includes means for activating one or more switches for testing and improving a transmission signal line using the relays and means for testing and emulating the transmission signal line based upon the activated switches. The apparatus also includes means for configuring the transmission signal line based upon a result of the means for testing and emulating.
According to still another aspect of the present invention, an apparatus for improving transmission quality on a transmission line by testing or evaluating and configuring the transmission line is provided. The apparatus includes a Universal Telephone Equipment Terminator (UTET) capable of implementing at least one of a test and an emulation, as well as a configuration on the transmission line. The configuration is performed in response to the test or the emulation. The UTET includes an input/output interface capable of receiving data and command signals and a micro-controller electrically coupled to the input/output interface and at least one relay electrically coupled to the micro-controller. The UTET also includes, both electrically coupled to the relay and the transmission line, at least one off-hook impedance emulation and measurement device and at least one on-hook impedance emulation and measurement device. The UTET also includes, both electrically coupled to the relay and the transmission line, at least one line-voltage measurement device, at least one resistive load termination switch and at least one active impedance termination switch. The micro-controller is adapted to receive and process the data and command signals from the input/output interface. The relay is adapted to activate a plurality of signal switches in response to a set of commands from the micro-controller. The off-hook impedance emulation and measurement device, the resistive load termination switch, the active impedance termination switch, the on-hook impedance emulation and measurement device, and the line-voltage measurement device are each adapted to be activated by the relay.
In yet another aspect of the present invention, another apparatus for testing, evaluating, and configuring a transmission line to improve transmission quality on the transmission line is provided. The apparatus includes a Universal Telephone Equipment Terminator (UTET) capable of implementing at least two of a test, a configuration, and an emulation on the transmission line. The apparatus is configured to communicate status and test signals on the transmission line to a second apparatus. The configuration is performed in response to the test or the emulation. The UTET includes an input/output interface capable of receiving data and command signals and a micro-controller electrically coupled to the input/output interface. The micro-controller is adapted to receive and process the data and command signals from the input/output interface. The UTET also includes at least one relay electrically coupled to the micro-controller. The relay is adapted to activate a plurality of signal switches in response to a set of commands from the micro-controller. The UTET also includes, electrically coupled to the relay and the transmission line, at least one off-hook impedance emulation and measurement device and at least one onhook impedance emulation and measurement device. The off-hook impedance emulation and measurement device and the on-hook impedance emulation and measurement device are both adapted to be activated by the relay. The UTET also includes, electrically coupled to the relay and the transmission line, at least one line-voltage measurement device and at least one resistive load termination switch. The line-voltage measurement device and the resistive load termination switch are both adapted to be activated by the relay. The UTET also includes at least one active impedance termination switch electrically coupled to the relay and the transmission line. The active impedance termination switch is also adapted to be activated by the relay.